2-DIMENSIONAL MODELING OF MAGNETICALLY DRIVEN RAYLEIGH-TAYLOR INSTABILITIES IN CYLINDRICAL Z-PINCHES

A two-dimensional computational methodology has been developed that us es a phenomenological representation of initial perturbations to model the evolution of magnetically driven Rayleigh-Taylor instabilities in a hollow Z pinch. The perturbed drive current waveform and x-ray outp ut obtained from the two-dimensional models differ qualitatively from the results of unperturbed (one-dimensional) models. Furthermore, the perturbed results reproduce the principle features measured in a serie s of capacitor bank-driven pulsed power experiments. In this paper we discuss the computational approach and the computational sensitivity t o initial conditions (including the initial perturbations). Representa tive examples are also presented of instability evolution during implo sions, and the results are compared with experimentally measured curre nt waveforms and visible framing camera images of perturbed implosions . Standard magnetohydrodynamic modeling, which includes instability gr owth in two dimensions, is found to reproduce the features seen in exp eriments. (C) 1996 American Institute of Physics.